The present invention relates to organopolysiloxane-polyimide copolymers based on the use of norbornane anhydride terminated organo polysiloxane and organic diamine.
Prior to the present invention, as shown by Holub, U.S. Pat. No. 3,325,450, and Heath et al, U.S. Pat. No. 3,847,867, silicon-polyimide copolymers were prepared by the reaction of aromatic bis(anhydride)s and amine organo-terminated polydiorganosiloxanes. For example, Holub shows the use of aminopropyl polydimethylsiloxane and amine butyltetramethyldisiloxane, as well as the employment of other diamines, for example, metaphenylenediamine. The production of such silicone-polyimide block polymers provide valuable compositions useful for example, as high temperature resistant electrical insulation.
As shown by copending application Ser. No. 395,932, norbornane-terminated polydiorganosiloxane of the formula, ##STR1## where R is selected from C.sub.(1-13) monovalent hydrocarbon radicals and substituted C.sub.(1-13) monovalent hydrocarbon radicals, R.sup. -R.sup.6 are selected from hydrogen, halogen and the same or different C.sub.(1-13) monovalent hydrocarbon radicals and substituted C.sub.(1-3) monovalent hydrocarbon radicals, Z is a divalent radical selected from --O-- and --C(R.sup.1).sub.2 --, Y is a radical selected from R and ##STR2## n is an integer equal to 0 to 2000 inclusive, m is a whole number equal to 0 to 500, and the sum of n+m is equal to 0 to 2000 inclusive, can be made by the hydrosilation of norbornene anhydride and derivatives thereof and a silicon hydride in the presence of a platinum catalyst as shown by the following equation: ##STR3## where R.sup.1 -R.sup.6, Z and n are as defined above.
Radicals included within R are, for example aryl radicals and halogenated aryl radicals, for example, phenyl, chlorophenyl, tolyl, xylyl, biphenyl, naphthyl, etc.; alkenyl radicals, for example, vinyl, allyl, cyclohexenyl, etc.; C.sub.(1-8) alkyl radicals and halogenated alkyl, for example, methyl, ethyl, propyl, butyl, octyl, etc.
Radicals included within R.sup.1 -R.sup.6 are, for example hydrogen, chloro, and R radicals as defined above.
Another procedure shown in copending application RD-14198 is by equilibrating a dianhydride within the scope of formula (1) where n is less than 2000 with a cyclic organopolysiloxane, for example octamethylcyclotetrasiloxane in the presence of an acid catalyst, for example sulfuric acid.
The present invention is based upon the discovery that silicone-polyimide copolymers having superior thermal oxidative stability and unusually high heat distortion temperatures can be made by effecting reaction between norbornane anhydride-terminated polydiorganosiloxane of formula (1) and organic diamine of the formula, ##STR4## and optionally with organic dianhydride of the formula, ##STR5## where Q is a tetravelent organo radical selected from the class consisting of ##STR6## where D is a member selected from ##STR7## where R.sup.8 is selected from hydrogen and R, R.sup.9 is a member selected from the class consisting of ##STR8## and divalent organic radicals of the general formula, ##STR9## where X is a member selected from the class consisting of divalent radicals of the formulas, ##STR10## where m is 0 or 1, y is a whole number from 1 to 5, R.sup.7 is a divalent C.sub.(2-20) organic radical selected from the class consisting of (a) aromatic hydrocarbon radicals having from 6-20 carbon atoms and halogenated derivatives thereof, (b) alkylene radicals and cycloalkylene radicals having from 2-20 carbon atoms, C.sub.(2-8) alkylene terminated polydiorganosiloxane, and (c) divalent radicals included by the formula, ##STR11## Q' is a member selected from the class consisting of ##STR12## x is a whole number from 1 to 5 inclusive.